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Section 6 Bus Controller
Pin Wait Insertion: Setting the WAITE bit in BCR to 1 enables wait insertion by means of the
WAIT pin. When external space is accessed in this state, a program wait is first inserted. If the
WAIT pin is low at the falling edge of φ in the last T
the WAIT pin is held low, T
This is useful when inserting four or more T
different external devices.
The WAITE bit setting applies to all areas. Pin waits cannot be inserted in DRAM space.
Figure 6.17 shows an example of the timing for insertion of one program wait state in 3-state
space.
Read access
Write access
Figure 6.17 Example of Wait State Insertion Timing
Rev. 4.00 Jan 26, 2006 page 164 of 938
REJ09B0276-0400
states are inserted until it goes high.
W
states, or when changing the number of T
W
Inserted
by program wait Inserted by WAIT pin
T
1
φ
WAIT
Address bus
AS
RD
Data bus
HWR, LWR
Data bus
indicates the timing of WAIT pin sampling.
Note:
or T
state, another T
2
W
T
T
T
T
2
w
w
Write data
state is inserted. If
W
states for
W
T
w
3
Read data
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